My daughter wore a pretty floral dress that she already had.

My eldest wore a nice hand-me-down black with white dotes strapless dress. You could also have a browse at a second hand store before you head into kmart or target

For year 6 I’d just get a nice dress from Target/big w etc & maybe some shoes if she doesn’t have any dressy/fancy ones.
I remember I got my first pair of (mini) heels for my yr 6 formal and thought I was just it!

My cousin had hers last year and she wore a pretty maxi dress and sandals. I did her hair and makeup to make her feel extra glam. An easy curled side pony and gold tones to keep it age appropriate but still ‘grown up’

My daughter had this when she was in year 7 and I managed to find a beautiful dress in Target and also got some lovely glittery sandals and spent just under $100. This was 6 years ago and we did her hair and make up at home. Other mum’s went crazy and spent $200 -$300 or a dress and had professional make up and hair done and pedicures. Some went overboard considering it was primary school. Some of the chain boutiques in shopping centres has nice dresses at reasonable prices.